Final answer:
The "9 + 0" pattern of microtubules is characteristic of primary (sensory) cilia, which differ from the flagella and motile cilia that have the "9 + 2 array".
Step-by-step explanation:
The "9 + 0" pattern of microtubules is associated with primary (sensory) cilia. The "9 + 0" pattern refers to the arrangement of microtubules within the cilia, with nine pairs of microtubule doublets surrounding a single pair in the center. Unlike the "9 + 2 array" of microtubules found in eukaryotic flagella and cilia, which consist of nine microtubule doublets surrounding a single microtubule doublet in the center, the 9 + 0 arrangement lacks the central pair and is characteristic of primary cilia. Primary cilia are present on nearly all animal cells and play important roles in sensory functions, such as signaling pathways that respond to environmental stimuli.