The most effective technique of malware propagation among the following list

Question Completion with Options:

A. Embedding & packing malcode in application programs

B. Replacing the Import-Address-Table (IAT)

C. Appending & prepending malcode into application programs

D. Embedding malcode in documents, such as MS O Office & PDF

Ε. Replicating malcode's source code

The most effective technique of malware propagation among the following list is:

A. Embedding & packing malcode in application program

Explanation:

Malware propagation becomes effective and replicates effortlessly when malicious codes (otherwise called malcodes, which are self-replicating malicious programs) are embedded and packed in application programs.  These usually take many years before they start to manifest, making them very difficult to detect.  They are often triggered by some set events.  Given the nature of malcodes and the culprits behind them, they are very dangerous to applications and pose substantial business risks.

the difference is right there dont you see it

(a) oldest