In the following passage some words have been deleted. Fill in the blanks with the help of the alternatives given. Select the most appropriate option for each number.
Passage:

The National Aeronautics and Space Administration’s (NASA) Viking Mission to Mars was(1).......... of two spacecraft. Viking 1 and Viking 2, (2)............. consisting of an orbiter and (3).......... lander. The primary objectives (4)............ to obtain images and samples(5)............. the Martian surface andsoil.