Select the phrase/connector from the given three options which can be used to form a single sentence from the two sentences given below, implying the same as expressed in the statement sentences.
Genetic evidence is starting to uncover. Smallpox first started attacking people.
1. when
2. hence
3. yet
1
Only 1
2
Only 2
3
Only 3
4
Both 1 and 2
5
None of these