Assume that: 1. the query processing engine can use four blocks in the buffer pool to hold disk blocks. 2. the records are fixed size, and each block contains 3 records. 3. there are two relations are r and s. their formats on disk are:

look at the engine block shown in the figure. the engine shown in this figure is a/an  

  a. four-cylinder, horizontally opposed engine.

  b. eight-cylinder, v-type engine.

  c. six-cylinder, v-type engine.

  d. four-cylinder, in-line engine