Explanation
Single-mode fiber is a type of optical fiber that has a small core diameter and allows only one mode of light to propagate. This reduces signal attenuation and increases transmission distance, making it suitable for long-distance communication networks. Single-mode fiber can carry data over thousands of kilometers without requiring repeaters or amplifiers. Single-mode fiber is also immune to electromagnetic interference and has a higher bandwidth than multimode fiber. Therefore, single-mode fiber is the best cable type for connecting sites on multiple continents. References: [CompTIA Network+ Certification Exam Objectives],
[Single-mode optical fiber - Wikipedia]
Single-mode fiber optic cable uses a single ray of light to transmit data. This allows it to achieve very low attenuation and high bandwidth.
Multimode fiber optic cable uses multiple rays of light to transmit data. This results in higher attenuation and lower bandwidth than single-mode cable.
Twisted pair copper cable uses two insulated copper wires to transmit data. It is less expensive than fiber optic cable, but it has higher attenuation and lower bandwidth.
When choosing a cable type for a long-distance application, it is important to consider the following factors:
Attenuation: The amount of signal loss that occurs over the length of the cable.
Bandwidth: The amount of data that can be transmitted over the cable per second.
Cost: The cost of the cable and installation.
Single-mode fiber optic cable is the best choice for long-distance applications because it has the lowest attenuation and highest bandwidth of any cable type. However, it is also the most expensive cable type.

Explanation
EIGRP stands for Enhanced Interior Gateway Routing Protocol, which is a hybrid routing protocol that uses a successor and a feasible successor to determine the best route to a destination. A successor is the next-hop router that has the lowest cost (or metric) to reach the destination, and a feasible successor is a backup router that has a cost that is less than the cost of the successor. EIGRP uses the successor and the feasible successor to achieve fast convergence and load balancing. EIGRP also uses a Diffusing Update Algorithm (DUAL) to maintain the routing table and avoid routing loops. IS-IS, OSPF, and BGP are other routing protocols that do not use a successor and a feasible successor, but rather use different algorithms and criteria to select the best route.
References
1: EIGRP - N10-008 CompTIA Network+ : 2.1
2: CompTIA Network+ N10-008 Certification Study Guide, page 150-151
3: CompTIA Network+ N10-008 Exam Subnetting Quiz, question 20
4: CompTIA Network+ N10-008 Certification Practice Test, question 9

Explanation
QSFP+ is a transceiver type that can support up to 40Gbps. It stands for Quad Small Form-factor Pluggable Plus and uses four lanes of data to achieve high-speed transmission. It is commonly used for data center and high-performance computing applications. References:
https://www.cisco.com/c/en/us/products/collateral/interfaces-modules/transceiver-modules/data_sheet_c78-6600

Explanation
In a half-duplex link, devices can only send or receive data at one time, not simultaneously. Late collisions occur when devices transmit data at the same time after waiting for a clear channel. One of the causes of late collisions is excessive cable length, which increases the propagation delay and makes it harder for devices to detect collisions. The link termination, device configuration, and device hardware are not likely to cause late collisions on a half-duplex link.