Which tool can an attacker use to attempt a DDoS attack?

A.
botnet

B.
Trojan horse

C.
virus

D.
adware

Explanation:
BD
Denial-of-service (DoS) attack and distributed denial-of-service (DDoS) attack. An example is using a botnet toattack a target system.
Source: Cisco Official Certification Guide, Table 1-6 Additional Attack Methods, p.16