    ‘Sentence 1: He” said. ‘there. were - ‘complex.  reasons, for. the’ increased. numbers. of. cases.  and: ‘scientists were. “only. just « beginning to.  understand the risk factors    “Sentence 2: However. ;-he. said , The reasons  “behind ” the: increase. :incidenéé are: tore’  cotnplex ‘and: were’just beginning to understand  the risk factors’,         