Choice A rationale:

Nucleoprotein (N) and phosphoprotein (P) are not responsible for viral entry and fusion in measles infection. These proteins are involved in viral replication and assembly, not the initial entry into host cells.

Choice B rationale:

Matrix protein (M) and large protein (L) are not responsible for viral entry and fusion in measles infection. The matrix protein plays a role in the assembly and structure of the virus, while the large protein is involved in viral replication and transcription.

Choice C rationale:

Fusion protein (F) and hemagglutinin protein (H) are the primary proteins responsible for viral entry and fusion in measles infection. The hemagglutinin protein allows the virus to bind to specific receptors on host cells, while the fusion protein facilitates the fusion of the viral envelope with the host cell membrane, allowing the virus to enter the cell.

Choice D rationale:

Nucleoprotein (N) and matrix protein (M) are not directly involved in viral entry and fusion. Nucleoprotein plays a role in protecting the viral RNA, and the matrix protein is involved in viral assembly and budding.